That rifle is categorically unsafe. YOU must give it to me to prevent you from getting inflicted with 99-osis. a most perilous and deadly disease.
Age is a little hard to say, the demi definitive way is this
In 1949, Savage began stamping a tiny, lightly impressed oval on the lower, front side of the "lever boss".
The “lever boss” is the extension of the lower part of the receiver into which the lever fits and rotates. Inside the oval, Savage stamped the letter "A" together with other numbers which are apparently inspector’s numbers.
On many Model 99 rifles, this “oval” is indistinct or difficult to read as are the letters and numbers inside the oval. On my own late model “EG”, serial #709XXX, made in 1953, only the upper case letter “E” and the rear half of the oval’s circumference (which looks like a large, faint, backwards letter "C") barely show on the lever boss. The front half of the oval’s circumference and whatever is inside the oval in front of the letter “E” are indistinguishable.
The letters “O” and “Q” were skipped and not used due to their similar appearance.
Here is a complete list of the Lever Boss Codes and their corresponding year of manufacture:
I believe the extended action was not released until 1957 and the tang safety was started in 1964, so between those years your gun should sit.